Device for electrically-driven liquid-cooled pump



Nov. 28, 1961 N. H. GRANQVIST 3,010,401

DEVICE FOR ELECTRICALLSPDRIVEN LIQUID-COOLED PUMP Filed Oct. 2, 1958 2 Sheets-Sheet 1 INVENTOR IV/LS HUGO GRANOV/ST ATTORNEYS PBY Nov. 28, 1961 N. H. GRANQVIST 3,010,401

DEVICE FOR ELECTRICALLY-DRXVEN LIQUID-COOLED PUMP Filed 001:. 2, 1958 2 Sheets-Sheet 2 INVENT OR IV/LS HUGO GRANOV/S T AT TOR/VE Y5 United States Patent 3,010,401 DEVICE FOR ELECTRICALLY-DRIVEN LIQUID-COOLED PUMP Nils Hugo Granqvist, Svannas, Ostertalje, Sweden, as-

signor to Aktiebolaget W. Dan Bergman, 'Sodertalje,

Sweden, a Swedish company Filed Oct. 2, 1958, Ser. No. 764,982 Claims priority, application Sweden Oct. 8, 1957 1 Claim. (Cl. 103-25) The present invention relates to a device for an electrically-driven, liquid-cooled pump.

More in particular, the invention relates to a pump of the type in which the shaft of the motor is arranged vertically in the working position of the pump, and in which the liquid cooling of the motor is achieved with the aid of the pumped liquid, the pump then being provided with a temperature-sensitive member arranged in such a way that when the parts of the pump adjoining the said member exceed a certain temperature it actuates a switch for shutting off the power supply in the motor circuit.

Pumps of the said type can be used, for instance, for pumping out water, the building industry, or for pumping sewer water.

The pumps will often work without supervision for a long time, and there is a risk that the cooling system will be clogged by sludge or that the pump will work without any transport of liquid.

If the temperature of the temperature-sensitive member in such cases exceeds the critical value, the power supply will automatically beshut off.

Pumps of designs hitherto known have mostly been provided with one single temperature-sensitive member, arranged at the pump element which according to experi ences has been the one most exposed to damages as a consequence of inadequate cooling.

However, it has often been possible for damages to accur in several different places in the pumps, without the risk therefore having been greatest at any special place. In such cases, it has been necessary to provide the pump with several temperature-sensitive members, which independent of each other can shut off the power supply to the motor. However, such pumps will have a considerably more complicated design, resulting in more costly procurement and maintenance.

The purpose of the present invention is to avoid the said disadvantages of the type of pump where there is a risk for damages in several places in the pump if the cooling becomes insufiicient, and this is achieved according to the invention by the upper end of the shaft of the electric motor being supported in a bearing placed in the immediate vicinity of both the rotor of the motor and the stator winding of the motor, the temperature-sensitive member then being fitted in the immediate vicinity of the said bearis design according to the invention will be described more in detail in the following, with reference to the attached drawing, in which FIGURE 1 is a longitudinal cross sectional view of a liquid cooled motor driven pump set having control means made in accordance with the present invention, and FIGURE 2 is a schematic longitudinal section of the uper part of the electrically-driven liquidcooled pump.

' port 12 leading from said ducts. According to the invention a temperature-dependent feeler member 8 of a type known in itself is fastened in the upper end 6' of the casing in the vicinity of the ball bearing and the stator windings 5. The member 8 is allowed to actuate a threeterminal switch 10 placed in a housing 9 above the member 8, in the feeding circuit of the motor, so that all the terminals break the contact at the exceeding of a pre-determined maximum permissible Working temperature of the motor units involved, viz the rotor 3, the stator 4 and the ball bearing 2, the heating of which units is transmitted to themem-ber 8 through both radiation and conduction.

It will be realized that the highest temperature will generally be found at the upper part of the casing, and thus one single feeler member with approximately the positioning shown is entirely sufiicient for switching off the power before any part of the motor has reached an unwanted temperature.

The invention is of course not limited to the design shown, which primarily relates to a three-phase-connected induction motor with a rotor of the short-circuited type. For other power feed conditions, the corresponding modification of the motor and/or the type of switch must be made.

It will be realized that the feeler member also serves as a protection for the motor in case of a short-circuiting of the windings, overload (e.g. if the pump wheel is jammed), a failure in the three-phase feed, etc. i

I claim:

A vertically aligned electric motor and pump set, said motor having rotor and stator members, and said motor and said pump having a common drive shaft and a bearing member for said shaft, said set having a casing with communicating ducts extending therethrough for circulating cooling liquid, a housing at one uppermost extremity of said casing sealedfrom said ducts, a temperature responsive switch enclosed within said housing, said pump having an outletport in communication with said ducts for forcing cooling liquid therethrough, said switch having an operative relationship to a temperature dependent feeler member, said feeler member being located in said casing in the vicinity of said bearing member and said rotor member for deenergizing said motor in response to an increase in temperature beyond predetermined limits.

, References Cited in the file of this patent UNITED STATES PATENTS 2,218,003 Hawley Oct. 15, 1940 2,473,485 Vickers June 14, 1949 2,483,007 iI-Iigham Sept. 27, 1949 2,514,693 Chapman July 11, 1950 2,518,597 Brooks Aug. 15, 1950 2,682,005 Hemphill ct a1 June 22, 1954 2,811,019 Courtney c- Oct. 29, 1957 2,923,461

Dallenbach Feb. 2, 1960 

